The invention relates to a process and an apparatus for injecting a radioactive sample of a substance into the reaction chamber of a reaction vessel for conversion of said substance, using an injection medium.
Faced with the looming worldwide shortage of crude oil, there has been an increasing trend in recent times to turn development towards the conversion of solid fossil fuels into high-energy liquid products. Most hard coals and brown coals or lignites for example are suitable for hydrogenating liquefaction. However, the pressures and temperatures required for carrying out the conversion operation are unusually high in comparison with other technical processes. Accordingly, high levels of requirement are made in regard to the structure of the reaction vessels and the mode of carrying such a process into effect. In connection with the way in which the process is carried out, it is important for example to establish the residence time of the coal to be converted in the reaction vessel, and thus the rate of throughput. A suitable way of doing that is measuring by means of radioactive substances which are introduced into the reaction vessel in order to ascertain the residence time thereof by means of counter tubes. However, when dealing with high-pressure and high-temperature reaction vessels, difficulties are encountered in regard to introducing radioactive trace substances of that kind into the reaction vessel and the reaction procedure which takes place therein and which, in the case of a hydrogenating liquefaction operation, is carried out under pressures of the order of magnitude of from 300 to 500 bars and at temperatures of the order of magnitude of from 700.degree. to 800.degree. C.
The idea of injecting substances into apparatuses or plants which are not under an increased pressure, by means of injection devices, for example simple injection nozzles, has long been known. In that procedure, the substances to be injected are disposed in a closed container comprising for example glass, which is inserted into and enclosed in the injection device and which is then crushed to liberate the substance to be injected, within the injection device. However, in that operation, difficulties may occur as glass splinters which are produced as a result of crushing the glass container can pass into the injection passage and can cause stoppages therein. Difficulties of that nature mean that it is not always possible to obtain precise measurement values. It will be appreciated that the known methods are out of the question from the outset, when the reaction vessels involve high pressures and high temperatures, as, when discharging the substances forming the result of the conversion operation from the reaction zone, and with the relief of pressure which occurs when that operation is performed, the energy conversion phenomena that occur, for example pressure is converted into flow energy or kinetic energy, are such that the valves and other equipment at the corresponding locations involved in that operation tend to be damaged or ruined by foreign bodies which may possibly be contained in the conversion substance. In any case, because of the operating conditions involved, the discharge members on the reaction vessels have a comparatively short operating life, even though they are made from high-grade materials, and renewing them is expensive. It would be prohibitive for the service life that can be achieved to be reduced due to influences as indicated above.